Быстрое преобразование между UInt и Int
У меня есть следующие методы
var photos = [MWPhoto] = [MWPhoto]()
func numberOfPhotosInPhotoBrowser(photoBrowser: MWPhotoBrowser!) -> UInt {
return self.photos.count
}
func photoBrowser(photoBrowser: MWPhotoBrowser!, photoAtIndex index: UInt) -> MWPhotoProtocol! {
return self.photos[index]
}
Однако для первого я получаю Int is not convertible to UInt (так как self.photos.count является Int
и для второго UInt is not convertible to Int - поскольку self.photos[ может принимать только Int для своего индекса.
Как я могу правильно преобразовать UInt в Int и обратно?
Ответы
Ответ 1
В первом случае тип возврата UInt, но вы возвращаете Int, поскольку count возвращает Int.
В основном UInt имеет инициализатор, который принимает варианты аргументов типов значений, таких как Int, CGFloat, Double или строка события и возвращает новый тип значения.
- UInt (8)//результат - это 8 значений типа UInt
- UInt (20.12)//результат - 20 значений типа UInt
- UInt (Double (10))//результат - это 10 значений типа UInt
- UInt ( "10" )//результат - это 10 значений типа UInt, обратите внимание, что это инициализатор с ошибкой, может быть значением или nil
-
func numberOfPhotosInPhotoBrowser(photoBrowser: MWPhotoBrowser!) -> UInt {
return UInt(self.photos.count)
}
Для второго индекса индекс массива ожидает значение Int, где вы передаете UInt, поэтому создайте новый тип Int из UInt,
func photoBrowser(photoBrowser: MWPhotoBrowser!, photoAtIndex index: UInt) -> MWPhotoProtocol! {
return self.photos[Int(index)]
}
Ответ 2
// initializing Int
var someInt: Int = 8
someInt
// Converting Int to UInt
var someIntToUInt: UInt = UInt(someInt)
someIntToUInt
// initializing UInt
var someUInt: UInt = 10
someUInt
// Converting UInt to Int
var someUIntToInt: Int = Int(someUInt)
someUIntToInt
Ответ 3
Если вы хотите, чтобы unsigned int с отрицательным значением, используйте UInt (bitPattern:)
let intVal = -1
let uintVal = UInt(bitPattern: intVal) // uintVal == 0xffffffffffffffff
Ответ 4
Добавьте это вне класса:
extension UInt {
/// SwiftExtensionKit
var toInt: Int { return Int(self) }
}
Затем просто позвоните:
self.photos[index].toInt
Ответ 5
Я так расстроился с параметрами Swift cryptic method bitPattern: и truncatingBitPattern: и моей неспособностью запомнить, какой из них использовать, когда я создал следующий класс, содержащий большое количество методов преобразования.
Я не обязательно рекомендую включить это в свою программу. Я уверен, что многие люди скажут, что Свифт пытается защитить нас от нас самих, и это саботирует эти усилия глупо. Так что, возможно, вам стоит просто сохранить этот файл как своего рода чит-лист, чтобы вы могли быстро определить, как сделать преобразование, и скопировать параметры в вашу программу, когда это необходимо.
Кстати, JDI означает "просто сделай это".
/// Class containing a large number of static methods to convert an Int to a UInt or vice-versa, and
/// also to perform conversions between different bit sizes, for example UInt32 to UInt8.
///
/// Many of these "conversions" are trivial, and are only included for the sake of completeness.
///
/// A few of the conversions involving Int and UInt can give different results when run on 32-bit
/// and 64-bit systems. All of the conversion where the bit size of both the source and the target
/// are specified will always give the same result independent of platform.
public class JDI {
// MARK: - To signed Int
// To Int8
public static func ToInt8(_ x : Int8) -> Int8 {
return x
}
public static func ToInt8(_ x : Int32) -> Int8 {
return Int8(truncatingBitPattern: x)
}
public static func ToInt8(_ x : Int64) -> Int8 {
return Int8(truncatingBitPattern: x)
}
public static func ToInt8(_ x : Int) -> Int8 {
return Int8(truncatingBitPattern: x)
}
public static func ToInt8(_ x : UInt8) -> Int8 {
return Int8(bitPattern: x)
}
public static func ToInt8(_ x : UInt32) -> Int8 {
return Int8(truncatingBitPattern: x)
}
public static func ToInt8(_ x : UInt64) -> Int8 {
return Int8(truncatingBitPattern: x)
}
public static func ToInt8(_ x : UInt) -> Int8 {
return Int8(truncatingBitPattern: x)
}
// To Int32
public static func ToInt32(_ x : Int8) -> Int32 {
return Int32(x)
}
public static func ToInt32(_ x : Int32) -> Int32 {
return x
}
public static func ToInt32(_ x : Int64) -> Int32 {
return Int32(truncatingBitPattern: x)
}
public static func ToInt32(_ x : Int) -> Int32 {
return Int32(truncatingBitPattern: x)
}
public static func ToInt32(_ x : UInt8) -> Int32 {
return Int32(x)
}
public static func ToInt32(_ x : UInt32) -> Int32 {
return Int32(bitPattern: x)
}
public static func ToInt32(_ x : UInt64) -> Int32 {
return Int32(truncatingBitPattern: x)
}
public static func ToInt32(_ x : UInt) -> Int32 {
return Int32(truncatingBitPattern: x)
}
// To Int64
public static func ToInt64(_ x : Int8) -> Int64 {
return Int64(x)
}
public static func ToInt64(_ x : Int32) -> Int64 {
return Int64(x)
}
public static func ToInt64(_ x : Int64) -> Int64 {
return x
}
public static func ToInt64(_ x : Int) -> Int64 {
return Int64(x)
}
public static func ToInt64(_ x : UInt8) -> Int64 {
return Int64(x)
}
public static func ToInt64(_ x : UInt32) -> Int64 {
return Int64(x)
}
public static func ToInt64(_ x : UInt64) -> Int64 {
return Int64(bitPattern: x)
}
public static func ToInt64(_ x : UInt) -> Int64 {
return Int64(bitPattern: UInt64(x)) // Does not extend high bit of 32-bit input
}
// To Int
public static func ToInt(_ x : Int8) -> Int {
return Int(x)
}
public static func ToInt(_ x : Int32) -> Int {
return Int(x)
}
public static func ToInt(_ x : Int64) -> Int {
return Int(truncatingBitPattern: x)
}
public static func ToInt(_ x : Int) -> Int {
return x
}
public static func ToInt(_ x : UInt8) -> Int {
return Int(x)
}
public static func ToInt(_ x : UInt32) -> Int {
if MemoryLayout<Int>.size == MemoryLayout<Int32>.size {
return Int(Int32(bitPattern: x)) // For 32-bit systems, non-authorized interpretation
}
return Int(x)
}
public static func ToInt(_ x : UInt64) -> Int {
return Int(truncatingBitPattern: x)
}
public static func ToInt(_ x : UInt) -> Int {
return Int(bitPattern: x)
}
// MARK: - To unsigned Int
// To UInt8
public static func ToUInt8(_ x : Int8) -> UInt8 {
return UInt8(bitPattern: x)
}
public static func ToUInt8(_ x : Int32) -> UInt8 {
return UInt8(truncatingBitPattern: x)
}
public static func ToUInt8(_ x : Int64) -> UInt8 {
return UInt8(truncatingBitPattern: x)
}
public static func ToUInt8(_ x : Int) -> UInt8 {
return UInt8(truncatingBitPattern: x)
}
public static func ToUInt8(_ x : UInt8) -> UInt8 {
return x
}
public static func ToUInt8(_ x : UInt32) -> UInt8 {
return UInt8(truncatingBitPattern: x)
}
public static func ToUInt8(_ x : UInt64) -> UInt8 {
return UInt8(truncatingBitPattern: x)
}
public static func ToUInt8(_ x : UInt) -> UInt8 {
return UInt8(truncatingBitPattern: x)
}
// To UInt32
public static func ToUInt32(_ x : Int8) -> UInt32 {
return UInt32(bitPattern: Int32(x)) // Extend sign bit, assume minus input significant
}
public static func ToUInt32(_ x : Int32) -> UInt32 {
return UInt32(bitPattern: x)
}
public static func ToUInt32(_ x : Int64) -> UInt32 {
return UInt32(truncatingBitPattern: x)
}
public static func ToUInt32(_ x : Int) -> UInt32 {
return UInt32(truncatingBitPattern: x)
}
public static func ToUInt32(_ x : UInt8) -> UInt32 {
return UInt32(x)
}
public static func ToUInt32(_ x : UInt32) -> UInt32 {
return x
}
public static func ToUInt32(_ x : UInt64) -> UInt32 {
return UInt32(truncatingBitPattern: x)
}
public static func ToUInt32(_ x : UInt) -> UInt32 {
return UInt32(truncatingBitPattern: x)
}
// To UInt64
public static func ToUInt64(_ x : Int8) -> UInt64 {
return UInt64(bitPattern: Int64(x)) // Extend sign bit, assume minus input significant
}
public static func ToUInt64(_ x : Int32) -> UInt64 {
return UInt64(bitPattern: Int64(x)) // Extend sign bit, assume minus input significant
}
public static func ToUInt64(_ x : Int64) -> UInt64 {
return UInt64(bitPattern: x)
}
public static func ToUInt64(_ x : Int) -> UInt64 {
return UInt64(bitPattern: Int64(x)) // Extend sign bit if necessary, assume minus input significant
}
public static func ToUInt64(_ x : UInt8) -> UInt64 {
return UInt64(x)
}
public static func ToUInt64(_ x : UInt32) -> UInt64 {
return UInt64(x)
}
public static func ToUInt64(_ x : UInt64) -> UInt64 {
return x
}
public static func ToUInt64(_ x : UInt) -> UInt64 {
return UInt64(x) // Does not extend high bit of 32-bit input
}
// To UInt
public static func ToUInt(_ x : Int8) -> UInt {
return UInt(bitPattern: Int(x)) // Extend sign bit, assume minus input significant
}
public static func ToUInt(_ x : Int32) -> UInt {
return UInt(truncatingBitPattern: Int64(x)) // Extend sign bit, assume minus input significant
}
public static func ToUInt(_ x : Int64) -> UInt {
return UInt(truncatingBitPattern: x)
}
public static func ToUInt(_ x : Int) -> UInt {
return UInt(bitPattern: x)
}
public static func ToUInt(_ x : UInt8) -> UInt {
return UInt(x)
}
public static func ToUInt(_ x : UInt32) -> UInt {
return UInt(x)
}
public static func ToUInt(_ x : UInt64) -> UInt {
return UInt(truncatingBitPattern: x)
}
public static func ToUInt(_ x : UInt) -> UInt {
return x
}
}
Вот несколько тестовых кодов:
public func doTest() {
// To Int8
assert(JDI.ToInt8(42 as Int8) == 42)
assert(JDI.ToInt8(-13 as Int8) == -13)
assert(JDI.ToInt8(42 as Int32) == 42)
assert(JDI.ToInt8(257 as Int32) == 1)
assert(JDI.ToInt8(42 as Int64) == 42)
assert(JDI.ToInt8(257 as Int64) == 1)
assert(JDI.ToInt8(42 as Int) == 42)
assert(JDI.ToInt8(257 as Int) == 1)
assert(JDI.ToInt8(42 as UInt8) == 42)
assert(JDI.ToInt8(0xf3 as UInt8) == -13)
assert(JDI.ToInt8(42 as UInt32) == 42)
assert(JDI.ToInt8(0xfffffff3 as UInt32) == -13)
assert(JDI.ToInt8(42 as UInt64) == 42)
assert(JDI.ToInt8(UInt64.max - 12) == -13)
assert(JDI.ToInt8(42 as UInt) == 42)
assert(JDI.ToInt8(UInt.max - 12) == -13)
// To Int32
assert(JDI.ToInt32(42 as Int8) == 42)
assert(JDI.ToInt32(-13 as Int8) == -13)
assert(JDI.ToInt32(42 as Int32) == 42)
assert(JDI.ToInt32(-13 as Int32) == -13)
assert(JDI.ToInt32(42 as Int64) == 42)
assert(JDI.ToInt32(Int64(Int32.min) - 1) == Int32.max)
assert(JDI.ToInt32(42 as Int) == 42)
assert(JDI.ToInt32(-13 as Int) == -13)
assert(JDI.ToInt32(42 as UInt8) == 42)
assert(JDI.ToInt32(0xf3 as UInt8) == 243)
assert(JDI.ToInt32(42 as UInt32) == 42)
assert(JDI.ToInt32(0xfffffff3 as UInt32) == -13)
assert(JDI.ToInt32(42 as UInt64) == 42)
assert(JDI.ToInt32(UInt64.max - 12) == -13)
assert(JDI.ToInt32(42 as UInt) == 42)
assert(JDI.ToInt32(UInt.max - 12) == -13)
// To Int64
assert(JDI.ToInt64(42 as Int8) == 42)
assert(JDI.ToInt64(-13 as Int8) == -13)
assert(JDI.ToInt64(42 as Int32) == 42)
assert(JDI.ToInt64(-13 as Int32) == -13)
assert(JDI.ToInt64(42 as Int64) == 42)
assert(JDI.ToInt64(-13 as Int64) == -13)
assert(JDI.ToInt64(42 as Int) == 42)
assert(JDI.ToInt64(-13 as Int) == -13)
assert(JDI.ToInt64(42 as UInt8) == 42)
assert(JDI.ToInt64(0xf3 as UInt8) == 243)
assert(JDI.ToInt64(42 as UInt32) == 42)
assert(JDI.ToInt64(0xfffffff3 as UInt32) == 4294967283)
assert(JDI.ToInt64(42 as UInt64) == 42)
assert(JDI.ToInt64(UInt64.max - 12) == -13)
assert(JDI.ToInt64(42 as UInt) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToInt64(UInt.max - 12) == 4294967283) // For 32-bit systems
#else
assert(JDI.ToInt64(UInt.max - 12) == -13) // For 64-bit systems
#endif
// To Int
assert(JDI.ToInt(42 as Int8) == 42)
assert(JDI.ToInt(-13 as Int8) == -13)
assert(JDI.ToInt(42 as Int32) == 42)
assert(JDI.ToInt(-13 as Int32) == -13)
assert(JDI.ToInt(42 as Int64) == 42)
assert(JDI.ToInt(-13 as Int64) == -13)
assert(JDI.ToInt(42 as Int) == 42)
assert(JDI.ToInt(-13 as Int) == -13)
assert(JDI.ToInt(42 as UInt8) == 42)
assert(JDI.ToInt(0xf3 as UInt8) == 243)
assert(JDI.ToInt(42 as UInt32) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToInt(0xfffffff3 as UInt32) == -13) // For 32-bit systems
#else
assert(JDI.ToInt(0xfffffff3 as UInt32) == 4294967283) // For 64-bit systems
#endif
assert(JDI.ToInt(42 as UInt64) == 42)
assert(JDI.ToInt(UInt64.max - 12) == -13)
assert(JDI.ToInt(42 as UInt) == 42)
assert(JDI.ToInt(UInt.max - 12) == -13)
// To UInt8
assert(JDI.ToUInt8(42 as Int8) == 42)
assert(JDI.ToUInt8(-13 as Int8) == 0xf3)
assert(JDI.ToUInt8(42 as Int32) == 42)
assert(JDI.ToUInt8(-13 as Int32) == 0xf3)
assert(JDI.ToUInt8(42 as Int64) == 42)
assert(JDI.ToUInt8(-13 as Int64) == 0xf3)
assert(JDI.ToUInt8(Int64.max - 12) == 0xf3)
assert(JDI.ToUInt8(42 as Int) == 42)
assert(JDI.ToUInt8(-13 as Int) == 0xf3)
assert(JDI.ToUInt8(Int.max - 12) == 0xf3)
assert(JDI.ToUInt8(42 as UInt8) == 42)
assert(JDI.ToUInt8(0xf3 as UInt8) == 0xf3)
assert(JDI.ToUInt8(42 as UInt32) == 42)
assert(JDI.ToUInt8(0xfffffff3 as UInt32) == 0xf3)
assert(JDI.ToUInt8(42 as UInt64) == 42)
assert(JDI.ToUInt8(UInt64.max - 12) == 0xf3)
assert(JDI.ToUInt8(42 as UInt) == 42)
assert(JDI.ToUInt8(UInt.max - 12) == 0xf3)
// To UInt32
assert(JDI.ToUInt32(42 as Int8) == 42)
assert(JDI.ToUInt32(-13 as Int8) == 0xfffffff3)
assert(JDI.ToUInt32(42 as Int32) == 42)
assert(JDI.ToUInt32(-13 as Int32) == 0xfffffff3)
assert(JDI.ToUInt32(42 as Int64) == 42)
assert(JDI.ToUInt32(-13 as Int64) == 0xfffffff3)
assert(JDI.ToUInt32(Int64.max - 12) == 0xfffffff3)
assert(JDI.ToUInt32(42 as Int) == 42)
assert(JDI.ToUInt32(-13 as Int) == 0xfffffff3)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt32(Int.max - 12) == 0x7ffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt32(Int.max - 12) == 0xfffffff3) // For 64-bit systems
#endif
assert(JDI.ToUInt32(42 as UInt8) == 42)
assert(JDI.ToUInt32(0xf3 as UInt8) == 0xf3)
assert(JDI.ToUInt32(42 as UInt32) == 42)
assert(JDI.ToUInt32(0xfffffff3 as UInt32) == 0xfffffff3)
assert(JDI.ToUInt32(42 as UInt64) == 42)
assert(JDI.ToUInt32(UInt64.max - 12) == 0xfffffff3)
assert(JDI.ToUInt32(42 as UInt) == 42)
assert(JDI.ToUInt32(UInt.max - 12) == 0xfffffff3)
// To UInt64
assert(JDI.ToUInt64(42 as Int8) == 42)
assert(JDI.ToUInt64(-13 as Int8) == 0xfffffffffffffff3)
assert(JDI.ToUInt64(42 as Int32) == 42)
assert(JDI.ToUInt64(-13 as Int32) == 0xfffffffffffffff3)
assert(JDI.ToUInt64(42 as Int64) == 42)
assert(JDI.ToUInt64(-13 as Int64) == 0xfffffffffffffff3)
assert(JDI.ToUInt64(Int64.max - 12) == (UInt64.max >> 1) - 12)
assert(JDI.ToUInt64(42 as Int) == 42)
assert(JDI.ToUInt64(-13 as Int) == 0xfffffffffffffff3)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt64(Int.max - 12) == 0x7ffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt64(Int.max - 12) == 0x7ffffffffffffff3) // For 64-bit systems
#endif
assert(JDI.ToUInt64(42 as UInt8) == 42)
assert(JDI.ToUInt64(0xf3 as UInt8) == 0xf3)
assert(JDI.ToUInt64(42 as UInt32) == 42)
assert(JDI.ToUInt64(0xfffffff3 as UInt32) == 0xfffffff3)
assert(JDI.ToUInt64(42 as UInt64) == 42)
assert(JDI.ToUInt64(UInt64.max - 12) == 0xfffffffffffffff3)
assert(JDI.ToUInt64(42 as UInt) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt64(UInt.max - 12) == 0xfffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt64(UInt.max - 12) == 0xfffffffffffffff3) // For 64-bit systems
#endif
// To UInt
assert(JDI.ToUInt(42 as Int8) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt(-13 as Int8) == 0xfffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt(-13 as Int8) == 0xfffffffffffffff3) // For 64-bit systems
#endif
assert(JDI.ToUInt(42 as Int32) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt(-13 as Int32) == 0xfffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt(-13 as Int32) == 0xfffffffffffffff3) // For 64-bit systems
#endif
assert(JDI.ToUInt(42 as Int64) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt(-13 as Int64) == 0xfffffff3) // For 32-bit systems
assert(JDI.ToUInt(Int64.max - 12) == 0xfffffff3)
#else
assert(JDI.ToUInt(-13 as Int64) == 0xfffffffffffffff3) // For 64-bit systems
assert(JDI.ToUInt(Int64.max - 12) == 0x7ffffffffffffff3)
#endif
assert(JDI.ToUInt(42 as Int) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt(Int.max - 12) == 0x7ffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt(Int.max - 12) == 0x7ffffffffffffff3) // For 64-bit systems
#endif
assert(JDI.ToUInt(42 as UInt8) == 42)
assert(JDI.ToUInt(0xf3 as UInt8) == 0xf3)
assert(JDI.ToUInt(42 as UInt32) == 42)
assert(JDI.ToUInt(0xfffffff3 as UInt32) == 0xfffffff3)
assert(JDI.ToUInt(42 as UInt64) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt(UInt64.max - 12) == 0xfffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt(UInt64.max - 12) == 0xfffffffffffffff3) // For 64-bit systems
#endif
assert(JDI.ToUInt(42 as UInt) == 42)
#if (arch(i386) || arch(arm))
assert(JDI.ToUInt(UInt.max - 12) == 0xfffffff3) // For 32-bit systems
#else
assert(JDI.ToUInt(UInt.max - 12) == 0xfffffffffffffff3) // For 64-bit systems
#endif
print("\nTesting JDI complete.\n")
}
